The aim of this study was to identify the proportion of recently published test accuracy studies which had been registered to evaluate whether registration had preceded study initiation and to assess whether registration included the published primary outcomes. The authors searched PubMed for primary studies evaluating the accuracy of tests or markers for screening, diagnosis, staging, monitoring, prediction or prognosis against a reference standard published in 536 high impact (>5) journals.

The authors identified 351 articles for inclusion of which 248 (71%) were diagnostic test accuracy studies and 103 (29%) were studies assessing prognostic tests. The authors identified 52 (15%) registered studies 27 of which included the registration number in the publication and 12 of which provided a reference to the publication in the registry. Of the studies that had been registered, 33% reported industry involvement; significantly more often than studies reporting another source of funding (11%), and studies without a (reported) source of funding (9%; p<0.001). Furthermore, 16/52 (31%) studies (5% of the total sample) had published primary outcomes before the study’s completion while among a further 12 (23%) the published primary aim had been registered but was somewhat different or vague than was reported in the published results. The authors reported that overall, very few test accuracy studies published in high impact journals are registered and only one in 22 test accuracy studies register their primary outcomes before study completion. These findings raise questions regarding transparency and the potential for selective reporting within published test accuracy studies.

Limitations stated by the author(s):

There were a number of limitations discussed by the study’s authors, including the unknown registration status of 126/351 (36%) of the included studies due to author non-reply to email inquiries. The restriction of the search to journals with impact factor of ≥5 could have introduced bias as it is possible that studies published in high impact journals are more likely to register studies and this could have overestimated results. Though the search limited to studies published between May and June 2012, the sample may have included older studies conducted before the trend toward registering study protocols.

Limitations stated by the reviewer(s):

Authors limited search to published articles and did not search for unpublished reports.